The C block spectrum includes a requirement sought by Internet leader Google that would make it accessible to any device or software application.

The winners of the hundreds of licenses were expected to be announced within days. Martin said the announcement would come after the FCC's four other commissioners approved an order he said is needed to formally end the auction.

The 700-megahertz spectrum is being returned by television broadcasters as they move to digital from analog signals in early 2009. The signals are valuable because they can go long distances and penetrate thick walls.

Potential winners in the auction, that began January 24 and went through 260 rounds of bidding, also include entrenched carriers like AT&T and possibly new competitors like Google, EchoStar and Cablevision.

Under rules set by the FCC, bidders' identities have been kept secret during the auction.

The order Martin has proposed to end the auction would "de-link" the one block of airwaves that did not meet its minimum bid requirement -- the "D" block -- from the rest of the spectrum.

Under FCC rules, the winner of the D block would have had to give police, firefighters and other public safety groups priority use during an emergency.

The FCC could decide to re-auction the D-block airwaves and possibly modify the rules and the minimum price to make it more attractive to potential bidders. FCC officials have declined to comment specifically on what they will do.